Quantification and localisation of damage in rat muscles after controlled loading; a new approach to study the aetiology of pressure sores

To obtain more insight in the aetiology of deep pressure sores, an animal m odel was developed to relate controlled external loading to local muscle da mage. The tibialis anterior muscle (TA) and overlying skin of a rat were co mpressed between indentor and tibia. Loads of 10, 70 and 250 kPa at skin su rface were applied for 2 or 6 h. During half of the 10 and 250 kPa experime nts interstitial fluid pressure (IFP) in the TA was measured. The TAs were excised 24 h after load application. Both amount and location of damage wer e assessed by histological examination using a semi-automated image-process ing program. In six of eleven loaded muscles damage was found. The damage w as located from superficial to deep muscle tissue in a zone never exceeding the diameter of the indentor. The IFP measurements interfered with the occ urrence of damage; application of 10 and 70 kPa loads only caused damage wh en combined with IFP measurements, whereas IFP measurements increased damag e at 250 kPa loads. The results showed that the developed animal model can be used to provoke local damage by applying a controlled load and that the amount and location of damage can be assessed using the newly developed tec hniques. (C) 2001 IPEM. Published by Elsevier Science Ltd. All rights reser ved.